Should fear of Zika virus keep Canadians from travelling this winter?

Every year, for as long as she can remember, Jessica Green has taken a winter holiday with family on a beach in Florida. But this year, with Green midway through her first pregnancy, she and her husband, Mitchell Radowitz, will be giving their usual vacation destination a pass.

The reason? Zika virus. The blood-borne virus can cause fevers, skin rashes and joint pain in those infected by the bite of an Aedes mosquito, and serious birth defects in infected babies.

Florida still has local Zika transmission, with 139 locally-acquired cases being reported since July, including six in a new area of Miami-Dade as recently as October.

Green isn’t taking any chances.

“The approach we’ve taken is to avoid the places we’ve been told not to go,” says Green, a Toronto-based corporate communications specialist. Instead, the couple will go to Palm Springs, California, for a “babymoon.”

“When it comes to something like this, it’s not just affecting you, it’s affecting your unborn child,” she says. “It becomes a much clearer decision. To put another life at risk is a whole other thing.”

As temperatures dip and Canadians begin thinking about winter holiday plans, here are some questions to consider about the Zika virus.

Should I cancel my winter travel plans?

The short answer is no – unless you’re pregnant, intending to get pregnant within six months of travel, or your immune system has been compromised by an illness like cancer.

“Zika’s really high on everyone’s mind,” says Isaac Bogoch, an infectious disease specialist at Toronto General Hospital. “But it’s a very mild disease in the average person. Eighty percent of those infected won’t know they have it and the 20 percent who do will likely have a very, very mild course.”

Zika symptoms can include fever, headache, pink eye, skin rash and joint and muscle pain. Once the infection has passed, survivors are left with immunity to future infections.

Earlier this month, the World Health Organization (WHO) lifted its “global health emergency” status for Zika. That’s not because spread of the virus has slowed, but because its spread has become an ongoing threat, like malaria or dengue, and needs more long-term thinking than an emergency suggests.

“We are not downgrading the importance of Zika. We are sending the message that Zika is here to stay,” said Peter Salama, executive director of the World Health Organization’s health emergencies program, during a media briefing.

While in very rare cases Zika can trigger Guillain-Barré syndrome, which can lead to paralysis, Zika’s most serious effects are usually seen in babies infected while in utero. This includes babies born with small heads (called microcephaly), which can cause brain damage and severe developmental delays.

“People who are pregnant or who are considering becoming pregnant in the near future basically should avoid traveling to Zika virus-affected areas. That’s the punchline,” Bogoch says.

What are the risks to pregnant women or couples planning a pregnancy?

It remains unclear when a fetus is most at risk for Zika-related birth defects, largely because microcephaly has only recently been discovered as a consequence of Zika infection.

Zika got its name from the Ugandan forest reserve where the virus was first identified in a rhesus monkey in the late 1940s. In 1948, researchers found the virus in mosquitoes, but it wasn’t until 1952 that the first human cases of Zika infection were reported, with the illness being described as mild.

The infection spread to mosquitoes in parts of Africa and Asia. Zika continued to be seen as a mild illness until reports from a 2008 outbreak in French Polynesia, in the remote South Pacific, showed it could cause Guillain-Barré syndrome in a relatively small number of patients.

In May 2015, Brazil confirmed an outbreak of Zika virus in a northeastern state and by July it was reporting that 49 cases led to Guillain-Barré syndrome, with all but two having a co-infection with dengue or chikangunya, two other mosquito-borne illnesses with symptoms similar to the Zika virus, a link researchers are exploring as a possible explanation for the severity of the symptoms.

It was just last year – October 2015 – that Brazilian doctors first reported that babies born to women infected with Zika were suffering severe birth defects, including microcephaly.

In July 2016, biologists at the Centers for Disease Control and Prevention’s Dengue branch used a range of outbreak scenarios to estimate that the risk of an infected fetus developing Zika-related birth defects was between one and 13 percent. Outbreak scenarios were used because the infection causes no symptoms in some people, making it difficult to know the true size of Brazil’s outbreak. The researchers also found “a strong association between the risk of microcephaly and infection risk in the first trimester and a negligible association in the second and third trimesters.”

Since most adults will carry the infection without ever feeling symptoms, even couples trying to get pregnant are warned to avoid Zika-endemic areas. The virus can be transmitted sexually and Bogoch says the virus has been detected in semen as long as six months after travel.

“The guidelines recommend males leaving a Zika-endemic area wait at least six months before attempting conception,” he says.

If only the woman was exposed and she becomes pregnant within two months of returning from a Zika-endemic area, she should be tested for Zika regardless of symptoms, says Philippe Lagacé-Wiens, assistant professor of Medical Microbiology and Infectious Diseases at the University of Manitoba and a consultant to the Travel and Tropical Medicine Clinic of the Winnipeg Regional Health Authority.

If only the man, or both the man and the woman were exposed and the woman becomes pregnant within six months of returning, she should be tested for Zika regardless of symptoms and they should immediately use condoms for the duration of the pregnancy.

Can Zika be detected in utero?

If a Zika infection is detected in a pregnant woman through blood and genetic testing, an amniocentesis can be performed to see if Zika can also be detected in utero.

However, Lagacé-Wiens says that while this can confirm a fetal infection, it doesn’t predict if or how the fetus will be affected by the infection.

“This is a very challenging situation for women who know they have been infected, have an apparently normal ultrasound but still could have an affected child,” he says. “A combination of amniocentesis genetic tests with serial ultrasounds should identify the majority of infected and affected fetuses, but some will certainly be missed, leaving women with a very difficult choice once they know the fetus is infected.”

What are the long-term effects of Zika for infected babies?

“We’re finding out, primarily from Brazil, that there are indeed more long-term effects that are starting to appear,” says Lagacé-Wiens. Some babies are born without any obvious signs of Zika infection, he says, while others may have the tell-tale shrunken skull that points to problems with the brain’s development.

However, experts following the development of babies born during Brazil’s outbreak have noticed further complications can appear as they age, such as seizures and other development disorders, including problems with both social and motor skills.

“There does appear to be not just severe effects such as a small head at birth, but a spectrum from completely normal to severely affected,” Lagacé-Wiens says.

While the frequency of these defects is unclear, a study published in the Lancet that followed infected pregnant women living in Rio de Janiero found 29 percent of their babies showed signs of a range of birth defects, including microcephaly.

What should I do if I travel to a Zika endemic area?

“Prevention is always worth more than trying to sort things out at the end,” says Lagacé-Wiens.

Since there is no vaccine against Zika – although U.S. scientists began human trials on an experimental vaccine in August of this year – travellers need to protect themselves from being bitten.

The Aedes mosquitoes that carry Zika bite during the day, so Lagacé-Wiens recommends using mosquito repellent and wearing light coloured, loose-fitting clothing that can keep mosquitoes away from the body.

Pregnant women who cannot avoid or delay travel to a Zika endemic area can and should use repellents with up to 30 percent DEET, he says.

How is Zika diagnosed and treated?

Zika testing in Canada is carried out at the National Microbiology Laboratory in Winnipeg and is usually limited to pregnant women who have been bitten by mosquitoes in a Zika-endemic area or who have experienced symptoms, Lagacé-Wiens says.

Two types of tests are performed, one looking for the virus, the other looking for antibodies to the virus.

There is no specific treatment for Zika and the virus usually passes within two weeks of infection.

What is my likelihood of contracting Zika if I travel to an endemic area?

“One of the hardest parts of this is determining what the actual risk is for a particular area,” Bogoch said. “Nobody really knows because surveillance in these areas is far from perfect.”

However, experts say the risk of travellers contracting Zika is relatively small.

Bogoch offers Florida as an example. Zika has been reported around Miami, yet with a population of about 20 million and about 100 million tourists visiting each year, only 139 cases have been contracted locally.

Travellers would seem to agree: earlier this month, Florida announced a record 85 million tourists visited the state in the first three quarters of 2016, a 5.5 percent increase over last year.

Canada has issued travel warnings for pregnant women and those planning to get pregnant for a suite of countries in the Caribbean, West Africa, Southeast Asia and the south Pacific, as well as the state of Florida.

In all instances, they recommend travellers take precautions against mosquito bites, which as Bogoch notes, can also carry dengue or chikangunya, both of which can lead to the fever, rash and joint ache-type symptoms that are similar to Zika, but often more severe. (Neither dengue nor chikangunya have been associated with birth defects but can cause miscarriage.)

The risk of contracting Zika can also depend on where travellers go, Lagacé-Wiens says, how long they stay and what activities they undertake while they’re there.

In the grand scheme of things, he says, Zika presents a very small risk for the average traveller, particularly compared to motor vehicle crashes or even traveller’s diarrhea.

“We can forget that travel is inherently risky,” he says.

That’s top of mind for Green, who says there are enough things to worry about when pregnant.

“There is a lot of, I guess I’d call it ‘fear-mongering’ when you’re pregnant,” she says. “This is one of those things that’s essentially low-hanging fruit where I can say, alright, I’m going to steer clear of this one.”

This document is provided under the terms of a CreativeCommons Attribution Non-commercial Share Alike license. The terms of the license are available at: http://creativecommons.org/licenses/by-nc-sa/3.0/. Attributions are to be made to HealthyDebate.ca, a project under the direction of Dr. Andreas Laupacis, at the Keenan Research Centre, Li Ka Shing Knowledge Institute of St. Michael’s Hospital.